Branching Agent Research Articles

Poly(aryl piperidinium)‐Based AEMs Utilizing Spirobifluorene as a Branching Agent

AbstractThe high‐performance anion exchange membranes (AEMs) are developed by incorporating 9,9′‐spirobifluorene as a 3D branching agent, addressing the common trade‐off between ion conductivity and dimensional/mechanical stability. By fine‐tuning the ratio of terphenyl to biphenyl and the amount of the branching agent, the AEM is refined, achieving high conductivity (≈190 mS cm−1 at 80 °C in 1 m KOH) with decent dimensional/mechanical properties, comparable to the recently reported state‐of‐the‐art membranes. Investigations using gas pycnometer and atomic force microscopy demonstrated that spirobifluorene enhances the fractional free volume around the membrane's backbone and more precisely modulates the separation between hydrophobic and hydrophilic domains, thus boosting both ion conductivity and mechanical stability. This membrane also displayed excellent chemical stability, with negligible degradation at 80 °C in 1 m KOH over 1,000 h. With such a membrane, an excellent cell performance is achieved, with a current density of 11.2 A cm−2 at 80 °C and 2 V in 1 m KOH, and 1.8 A cm−2 at 80 °C and 2 V in pure water conditions. The in situ membrane stability test, conducted at a constant current density of 1 A cm−2 for 500 h, showed no significant degradation.

Network homogeneity on linear and nonlinear viscoelasticity of polyethylene terephthalate vitrimers

Designing network topology with tunable dynamics and rheology behaviors is the key for vitrimers applications. In this study, PET vitrimers with varying crosslinking density and network homogeneity were created by using different Mw of precursors and branching agents (catalysts). Our results show that the dynamic network formed by propane-type branching agent such as 1,3-bis[tris(hydroxymethyl) methylamino] propane (BIS-TRIS propane), is more uniform due to steric hindrance effect compared to 2,2-Bis(hydroxymethyl)-2,2′,2″-nitrilotriethanol (BIS-TRIS). The thermal behavior of PET vitrimers was investigated by non-isothermal experiments, including glass transition and crystallization process. In particular, rheology behavior is sensitive to network structure and bond exchange process. The linear viscoelasticity (LVE) region of PET vitrimers is characterized by constructed pseudo-master curves that are guided by two distinct relaxation mechanisms: Rouse-type relaxation of strands and terminal relaxation of the network. Each relaxation mechanism is associated with a unique activation energy. The mechanical and processing properties of the PET vitrimers are reflected in their plateau modulus and characteristic relaxation time, which varies depending on the network topology. Based on the LVE analysis, we further investigated nonlinear rheology of PET vitrimers under extensional flow. Our results indicate that PET vitrimers exhibit significant strain hardening behavior, but display distinct stretching trends, corresponding to polymer melts' ductility. The ductility of materials decreases with a decrease in precursor's molecular weight (Mw), but improved with enhanced network homogeneity. Therefore, the crosslinking density and network homogeneity of dynamic network can be selectively tailored using appropriate precursors and branching agents to meet various industrial applications.

Triptycene Branched Poly(aryl-co-aryl piperidinium) Electrolytes for Alkaline Anion Exchange Membrane Fuel Cells and Water Electrolyzers.

Alkaline polymer electrolytes (APEs) are essential materials for alkaline energy conversion devices such as anion exchange membrane fuel cells (AEMFCs) and water electrolyzers (AEMWEs). Here, we report a series of branched poly(aryl-co-aryl piperidinium) with different branching agents (triptycene: highly-rigid, three-dimensional structure; triphenylbenzene: planar, two-dimensional structure) for high-performance APEs. Among them, triptycene branched APEs showed excellent hydroxide conductivity (193.5 mS cm-1 @80 °C), alkaline stability, mechanical properties, and dimensional stability due to the formation of branched network structures, and increased free volume. AEMFCs based on triptycene-branched APEs reached promising peak power densities of 2.503 and 1.705 W cm-2 at 75/100 % and 30/30 % (anode/cathode) relative humidity, respectively. In addition, the fuel cells can run stably at a current density of 0.6 A cm-2 for 500 h with a low voltage decay rate of 46 μV h-1 . Importantly, the related AEMWE achieved unprecedented current densities of 16 A cm-2 and 14.17 A cm-2 (@2 V, 80 °C, 1 M NaOH) using precious and non-precious metal catalysts, respectively. Moreover, the AEMWE can be stably operated under 1.5 A cm-2 at 60 °C for 2000 h. The excellent results suggest that the triptycene-branched APEs are promising candidates for future AEMFC and AEMWE applications.

Triptycene Branched Poly(aryl‐co‐aryl piperidinium) Electrolytes for Alkaline Anion Exchange Membrane Fuel Cells and Water Electrolyzers

AbstractAlkaline polymer electrolytes (APEs) are essential materials for alkaline energy conversion devices such as anion exchange membrane fuel cells (AEMFCs) and water electrolyzers (AEMWEs). Here, we report a series of branched poly(aryl‐co‐aryl piperidinium) with different branching agents (triptycene: highly‐rigid, three‐dimensional structure; triphenylbenzene: planar, two‐dimensional structure) for high‐performance APEs. Among them, triptycene branched APEs showed excellent hydroxide conductivity (193.5 mS cm−1@80 °C), alkaline stability, mechanical properties, and dimensional stability due to the formation of branched network structures, and increased free volume. AEMFCs based on triptycene‐branched APEs reached promising peak power densities of 2.503 and 1.705 W cm−2 at 75/100 % and 30/30 % (anode/cathode) relative humidity, respectively. In addition, the fuel cells can run stably at a current density of 0.6 A cm−2 for 500 h with a low voltage decay rate of 46 μV h−1. Importantly, the related AEMWE achieved unprecedented current densities of 16 A cm−2 and 14.17 A cm−2 (@2 V, 80 °C, 1 M NaOH) using precious and non‐precious metal catalysts, respectively. Moreover, the AEMWE can be stably operated under 1.5 A cm−2 at 60 °C for 2000 h. The excellent results suggest that the triptycene‐branched APEs are promising candidates for future AEMFC and AEMWE applications.

Fabrication of recyclable and biodegradable PBAT vitrimer via construction of highly dynamic cross-linked network

The emergence of biodegradable materials has not satisfactorily addressed the issue of plastic waste management, owing to their high cost and poor mechanical performance and durability that impair their potential to replace traditional plastics. In this study, a dynamic cross-linked network with robust remoldability was fabricated in PBAT. Transesterification catalysts were employed to catalyze the reaction of β-hydroxyl groups produced from the branching reaction of polyester end groups and epoxy branching agents with the abundant ester groups of PBAT to produce biodegradable PBAT vitrimers. Swelling experiments, DMA tests and stress relaxation experiments confirmed the presence of the dynamic cross-linking structure, while rheological analysis demonstrated that the highly catalyst-loaded PBAT vitrimer dynamic cross-linked network could achieve chain relaxation by exchanging bonds quickly at physical entanglement and chemical cross-linking points. Multiple recycling experiments further demonstrated that the robust dynamic cross-linked network of PBAT vitrimers possessed both strong stress relaxation ability and remoldability, thus conferring excellent recyclability to PBAT. Upon recycling 4 times, the elongation at break of the PBAT vitrimer remained at 93.46 % (with a tensile strength retention of 85.99 %), whereas the raw PBAT could only maintain an elongation at break of 28.01 % (with a tensile strength retention of 56.09 %). TGA and hydrolysis experiments revealed that PBAT vitrimers exhibited better degradation performance relative to raw PBAT. PBAT vitrimers, featuring excellent mechanical performance and durability, can be recycled several times in easily recyclable settings, thus reducing production costs, and finally biodegrade after disposal, thereby serving as a viable replacement for traditional plastics. This straightforward and practicable approach provides a solution for plastic waste management.

Branched thermotropic liquid crystal polymer with favourable processability and dielectric properties

Thermotropic Liquid Crystal Polymer (TLCP) has emerged as a promising material for 5G mm-wave antennas due to its low dielectric constant and loss at high frequencies. However, its low melt viscosity, inadequate melt elasticity, and rigid rod-like macromolecular chain with easy orientation pose a significant challenge in the production of isotropic films. In this study, in order to improve the melt viscosity and melt elasticity of TLCP, a multifunctional epoxide-based branching agent (ADR 4468) was applied to produce branched TLCP. The impact of the branched structure on linear viscoelastic, thermal, mechanical, and dielectric performance was investigated. Results from linear rheological characterizations indicated that complex viscosity and storage modulus of modified TLCP samples were significantly enhanced, indicating the presence of long-chain branches. The mechanical performance of modified samples was scarcely affected by the concentration of ADR 4468, with a tensile strength of approximately 245 MPa, and Charpy notched impact strength of approximately 30 KJ/m2. However, with an increase in ADR 4468 content, the dielectric constant increased (from 3.25 to 3.30 at 10 GHz) as well as the dielectric loss (from 1.36 × 10−3 to 2.14 × 10−3 at 10 GHz). Based on the overall performance, the optimal content of ADR 4468 was found to be about 2–3 wt%. These findings offer insights into the potential applications of modified TLCPs as substrates for 5G mm-wave antennas.

Effect of a Hydrophobic Branching Agent in Physically Cross‐Linked Hydrogels with Shape‐Memory and Self‐healing Abilities

AbstractPhysically crosslinked hydrogels consisting of polyacrylamide (Aam) and polyoctadecylacrylate (C18A) blocks, leading to hydrophilic and hydrophobic domains respectively, are prepared by micellar polymerization. A multifunctional monomer (divinylbenzene, DVB), is also employed to create branched chains. The effect of the polymer composition and the amount of the branching agent on the material characteristics are evaluated. The melting enthalpies of the hydrophobic domains increase as the n‐octadecyl acrylate unit amount increases and, in a parallel fashion, an increase in the mechanical modulus G' of the hydrogel is observed. Furthermore, G′ increases as the DVB concentration increases. Self‐healing behavior is also demonstrated both visually and by rheological measurements. Finally, once heated above the melting temperature (Tm), these hydrogels can be deformed into different shapes that can be fixed on cooling. Then, heating again above Tm, the original shape is recovered thus indicating shape memory characteristics.

The Use of Branching Agents in the Synthesis of PBAT.

Biodegradable polyesters represent an advanced alternative to polyolefin plastics in various applications. Polybutylene adipate terephthalate (PBAT) can compete with polyolefins in terms of their mechanical characteristics and melt processing conditions. The properties of PBAT depend on the molecular weight, dispersity, and architecture of the copolymer. Long-chain branching (LCB) of the PBAT backbone is an efficient method for the improvement of the copolymer characteristics. In the present work, we studied branching agents (BAs) 1–7 of different structures in the two-stage polycondensation of 1,4-butanediol, dimethyl terephthalate, and adipic acid and investigated the composition and melt rheology of the copolymers. According to the results of the research, 1,1,1-tris(hydroxymethyl)ethane 2 and 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid 5 outperformed glycerol 1 as BAs in terms of shear thinning behavior and viscoelasticity.

Phototoxicity effects of NIR-irradiated cesium tungsten oxide (Cs0.33WO3) nanoparticles on zebrafish embryos: A direct immersion study

Nanoparticles (NPs) with feature sizes ranging between 1 nm and 100 nm have increasingly gained momentum for their versatile functionality as the pharmaceutical agents in many branches of biomedical research and clinical experiments. However, NPs’ inherent material toxicity and the concomitant adverse effects of their function, such as photo-physical properties, often remain a major concern over the issues of environmental safety and human health, and require a thorough assessment before a wide-spread usage can be complied. This research herein investigates the intrinsic and photothermal toxicity of Cs0.33WO3 NPs solution in zebrafish larvae through a direct immersion method. Experimentally, the survival, hatching and malformation rates of zebrafish embryo/larvae as functions of the NP feature sizes, concentration and duration of photothermal dose were examined and analyzed. This study verified that the Cs0.33WO3 NPs has an intrinsic toxicity on a scale of a fraction of 1 mg/ml, and the phototoxicity effect of the NIR-irradiated NPs, when irradiated for 30 min, can affect the embryogenesis of zebrafish larvae and causes 60% and 50% in the survival and delayed hatching rates, respectively, as well as a severe malformation.

Convergent Synthesis of Branched Metathesis Polymers with Enyne Reagents.

Branched polymers have found utility in an array of fields due to the high density of functional groups combined with unique physical properties. Despite the abundant methods reported to synthesize various branched structures, controlling parameters such as the location of branch points and molecular weight distribution still remains a challenge. This report explores the ability of enyne-containing branching agents to synthesize star and miktoarm star polymers through a convergent synthesis pathway using ring-opening metathesis polymerization (ROMP). The branching agents contain an enyne metathesis terminator covalently linked to a norbornene monomer. When these agents are introduced into a living ROMP, macromonomers are generated in situ that continue to propagate via a grafting-through process with the remaining living chains. This strategy permits control over the degree of polymerization of the star arms, control of the number of star arms, and chain-extension with additional monomer to produce functional asymmetric miktoarm star polymers.

Synthesis of Hyperbranched Polyisoprene by Isoprene/Dimethyl‐di‐2,4‐Pentadieneyl‐(E,E)‐Silane Copolymerization Catalyzed with Half‐Sandwich Scandium Complex

AbstractA series of hyperbranched polyisoprenes (HBPIps) are synthesized by copolymerization of isoprene and a novel dipentadiene‐containing branching agent dimethyl‐di‐2,4‐pentadieneyl‐(E,E)‐silane (DMDPS) catalyzed by the half‐sandwich scandium complex (C5Me4SiMe3)Sc(CH2C6H4NMe2‐o)2/[Ph3C][B(C6F5)4]. Due to the high activity of DMDPS in copolymerization, and the very similar reactivity of the two pentadieneyl groups in DMDPS, the gelation reaction is successfully avoided in the highly branched products. The structural parameter branching factor (g′) of the HBPIps is determined to evaluate the branching degree. It is proved that in the polymerization both the concentration of DMDPS and isoprene exhibits significant influence on branching degree of HBPIps. By using the DMDPS as branching agent and simply controlling the polymerization conditions, high branching degree of g′ = 0.35 is achieved.

Synthesis and Characterization of Novel Nanoporous Gl-POSS-Branched Polymeric Gas Separation Membranes.

Novel nanoporous Gl-POSS-branched polymers based on the macroinitiator of anionic nature, 2,4-toluene diisocyanate, and octaglycidyl polyhedral oligomeric silsesquioxane (Gl-POSS) were obtained as gas separation membranes. The synthesis of polymers was carried out using various loads of Gl-POSS. It was found that the main reaction proceeding with 2,4-toluene diisocyanate is the polyaddition, accompanied by the isocyanate groups opening of the carbonyl part. This unusual opening of isocyanate groups leads to the formation of coplanar acetal nature polyisocyanates (O-polyisocyanate). The terminal O-polyisocyanate links initiate the subsequent opening of the epoxide rings in Gl-POSS. As a result, Gl-POSS serves as a hard and bulky branching agent and creates the specific framing supramolecular structure, which leads to the formation of nanopores in the polymer, where the flexible polyether components are located inside the cavities. Thermal, mechanical, physical, and chemical properties of the obtained polymers were studied at various Gl-POSS contents in the polymer matrix. It was found that these polymers show high selectivity of gas transport properties for pure ammonia relative to nitrogen and hydrogen at ambient temperature. Measurements showed that the gas permeability coefficients and the values of ideal selectivity were in a non-additive dependence to the Gl-POSS content.

Leaf pinching and phytohormones - two important components for the branching induction on sweet cherry

The promising branching agent cyclanilide [1-(2,4-dichlorophenylaminocarbonyl)-cyclopropane carboxylic acid] is not permitted in the EU and the low vigour rootstocks preferred by growers make the branching of young sweet cherry (Prunus avium) trees difficult in the temperate zone production regions. To increase the number and length of new branches (“feathers”) on such trees, chemical (6-benzyladenine [BA], gibberellic acid [GA<sub>4/7</sub>]), mechanical (leaf pinching, summer notching) and various combined treatments were tested from 2015–2018. The numbers of feathers divided into three different lengths (1–10 cm, 10–30 cm and > 30 cm) were assessed as the main indicator of quality, supplemented with other morphological characteristics. Summer notching induced an insufficient number of feathers and led to some negative effects on the trees. The number of feathers from BA or BA with GA<sub>4/7</sub> treatment also was insufficient. The effect of pinching alone was variable. The number of all feathers generally was highest when pinching was combined with BA, regardless of the year or cultivar.

Branched poly(biphenylene‐co‐sulfone)ether ion exchange membranes containing perfluorocyclobutane groups for fuel cell applications

ABSTRACTA series of branched poly(biphenylene‐co‐sulfone) ion exchange membranes containing perfluorocyclobutane groups were prepared for fuel cells. Two bifunctional trifluorovinyloxy‐terminated monomers (sulfonable 4,4′‐bis(trifluorovinyloxy)biphenyl and insulfonable 4,4′‐sulfonyl‐bis(trifluorovinyloxy)biphenyl) and a trifunctional trifluorovinyloxy‐terminated branching agent (1,1,1‐tris(4′‐trifluorovinyloxyphenyl)ethane) were synthesized and terpolymerized via thermal [2π + 2π] cyclodimerization to obtain partially fluorinated and branched polymers containing 0–5 mol% of the branching agent. They were then postsulfonated by chlorosulfonic acid at room temperature, cast as membranes, and characterized to evaluate their electrochemical properties for fuel cell applications. As the branching agent content was increased, their polydispersity values highly increased, indicating they became highly branched. It was confirmed that higher branching agent content also increased the ion exchange capacity, water uptake, and proton conductivity of the branched ion exchange membranes containing perfluorocyclobutane groups. This indicates that their electrochemical properties can be easily controlled by the degree of branching. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48373.

Accurate density functional theory (DFT) protocol for screening and designing chain transfer and branching agents for LDPE systems

This work emphasizes the importance of considering multiple reaction pathways when estimating the rate parameters for free radical polymerization using DFT.

Use of Plant Growth Regulators for Feathering and Flower Suppression of Apple Nursery Trees

The use of highly feathered trees can make high-density apple plantings more profitable through enhanced precocity and increased early yield. Currently, nurseries are asked to provide highly feathered trees with wide branch crotch angles. The use of plant growth regulators (PGRs) can play a key role when it comes to branch induction; however, dose and timing both need to be tested to enhance branching without compromising other tree quality attributes. Over the last 4 years, we have conducted studies of the use of MaxCel® (6-benzyladenine) and Promalin® (a mixture of 1.8% 6-benzyladenine and 1.8% GA4+7) in comparison with Tiberon™ SC (cyclanilide) at several nurseries in NY, WA, DE, Ontario (Canada), and Chile. The best results were obtained with four applications of MaxCel® or Promalin® (400 mg·L−1) beginning when leader growth reached 70 cm above the soil line and reapplied at 10–14 days intervals. Promalin® was a slightly less effective branching agent than MaxCel®. On the other hand, Promalin® stimulated leader growth resulting in improved final tree height, whereas MaxCel® induced the widest branch angles. Overall, we observed good response and quality ratings with ‘Cameo’, ‘Cripps Pink’, ‘Enterprise’, ‘Fuji’, ‘Ambrosia’, ‘Crimson Crisp’, ‘Gingergold’, and ‘Granny Smith’, whereas less quality ratings were observed on ‘Ambrosia’, ‘Cortland’, ‘Goldrush’, ‘Honeycrisp’, and ‘Suncrisp’. Response with ‘Gala’ varied depending on the temperature range. Multiple sprays of Gibberellins (GA4+7, or GA3) at 250 mg·L−1 applied to nursery trees in the late summer inhibited flower bud development and flowering in the orchard the next year. This reduces the risk of fire blight infection in newly planted trees.

Kinetic Modeling of the Thermal Destruction of Nitrogen Mustard Gas.

The destruction of stockpiles or unexploded ammunitions of nitrogen mustard (tris(2-chloroethyl)amine, HN-3) requires the development of safe processes. The thermal destruction of this kind of compound is one of the most efficient method of destruction. Because of the high-level of toxicity of this chemical, there is a considerable lack of knowledge on the chemical kinetics at high temperatures. In this study, a detailed chemical kinetic model for the pyrolysis of nitrogen mustard gas is developed based on a large number of thermokinetic parameters calculated with theoretical chemistry. The thermal decomposition of HN-3 is shown to mainly proceed through stepwise dechlorination with Cl-atom being the principal chain carrier. The successive losses of chlorine atom mainly lead to unsaturated amines without chlorine groups. Theoretical calculations demonstrated that the thermal decomposition of these compounds ultimately lead to the formation of pyrrole, which can accumulate at low temperature. At higher temperatures, pyrrole yields HCN and acetylene. Simulations also predict that about 52% of the total flux of decomposition of HN-3 leads to the formation of N,N-diethenyl-2-chloroethylamine (P29), which acts as a chain branching agent because its unimolecular decomposition is preponderant and produces one chlorine and one hydrogen atoms. Comparisons with the simulated reactivity of sulfur mustard gas are also performed and show that HN-3 is more reactive that the former toxic. The higher number of chlorine atoms in HN-3 compared to sulfur mustard (3 vs 2) and the formation of the chain branching intermediate P29 during its decomposition explain this behavior.

Biodegradable inorganic-organic hybrids of methacrylate star polymers for bone regeneration.

Bioactive glasses can regenerate bone but are brittle. Hybrids can overcome this problem as intimate interactions between glass and polymer creates synergetic properties. Implants have previously been made with synthetic polymers that degrade by water, however, they degrade catastrophically, causing rapid loss of strength. Polymers that degrade by biological agents may degrade at a more controlled rate, which should give time for tissue repair and transfer of load. Previously, hybrids made with star shaped poly(methyl methacrylate-co-3-(trimethoxysilyl)propyl methacrylate) (p(MMA-co-TMSPMA)) showed enhanced properties. However, methacrylates are not bio-degradable. Here, star shaped p(MMA-co-TMSPMA) was synthesized with a core that can be cleaved by glutathione, a tripeptide. On exposure to glutathione, the hybrid degraded, producing products with molecular weights below the kidney filtration threshold.

A novel branched side-chain-type sulfonated polyimide membrane with flexible sulfoalkyl pendants and trifluoromethyl groups for vanadium redox flow batteries

Abstract A novel branched side-chain-type sulfonated polyimide (6F-s-bSPI) membrane with accessible branching agents of melamine, hydrophobic trifluoromethyl groups ( CF3), and flexible sulfoalkyl pendants is prepared by a high-temperature polycondensation and post-sulfonation method for use in vanadium redox flow batteries (VRFBs). The chemical structure of the 6F-s-bSPI membrane is confirmed by ATR-FTIR and 1H NMR spectra. The physico-chemical properties of the as-prepared 6F-s-bSPI membrane are systematically investigated and found to be strongly related to the specially designed structure. The 6F-s-bSPI membrane offers a reduced cost and possesses a significantly lowered vanadium ion permeability (1.18 × 10−7 cm2 min−1) compared to the linear SPI (2.25 × 10−7 cm2 min−1) and commercial Nafion 115 (1.36 × 10−6 cm2 min−1) membranes, prolonging the self-discharge duration of the VRFBs. In addition, the VRFB assembled with a 6F-s-bSPI membrane shows higher coulombic (98.3%–99.7%) and energy efficiencies (88.4%–66.12%) than that with a SPI or Nafion 115 membrane under current densities ranging from 20 to 100 mA cm−2. Moreover, the VRFB with a 6F-s-bSPI membrane delivers a stable cycling performance over 100 cycles with no decline in coulombic and energy efficiencies. These results show that the branched side-chain-type structure is a promising design to prepare excellent proton conductive membranes.

Long chain branched poly(butylene succinate‐co‐terephthalate) copolyesters using pentaerythritol as branching agent: Synthesis, thermo‐mechanical, and rheological properties

ABSTRACTIncorporating long chain branching (LCB) structure into biodegradable copolyesters can effectively improve their melt strength and film blowing processability. However, branching also results in deterioration of crystallizability which is also important for copolyester properties and processing. In this study, pentaerythritol (PER) was used as branching agent (BA) instead of previous used in‐situ BA, diglycidyl 1,2,3,6‐tetrahydrophthalate (DGT), to synthesize LCB poly(butylene succinate‐co‐terephthalate) (PBST) copolyesters. The chain structure was characterized and the effects of branching on thermal transition, mechanical, and rheological properties were investigated. Similar to DGT, copolymerizing small amount of PER (0.1–0.4 mol %) generates LCB structure and, therefore, improves the melt elasticity or strength and tensile modulus but reduces the elongation at break. Differing from DGT, PER showed higher branching efficiency, and PER‐branched PBSTs exhibited unchanged or even improved crystallization ability compared with linear PBST. The improved melt strength coupled with good crystallizability will endow PER‐branched PBSTs with better film blowing processability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2017,134, 44544.